Android Direction Sensor

Question

Is it possible to find out in which direction the phone is pointing, looking at the camera’s preview, or do you need the phone to be flat, like a compass.

thank

Answer 1

Yes - the following code should complete the task

public class Test extends Activity  implements SensorEventListener{

public static float swRoll;
public static float swPitch;
public static float swAzimuth;


public static SensorManager mSensorManager;
public static Sensor accelerometer;
public static Sensor magnetometer;

public static float[] mAccelerometer = null;
public static float[] mGeomagnetic = null;


public void onAccuracyChanged(Sensor sensor, int accuracy) {
}

@Override
public void onSensorChanged(SensorEvent event) {
    // onSensorChanged gets called for each sensor so we have to remember the values
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
        mAccelerometer = event.values;
    }

    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
        mGeomagnetic = event.values;
    }

    if (mAccelerometer != null && mGeomagnetic != null) {
        float R[] = new float[9];
        float I[] = new float[9];
        boolean success = SensorManager.getRotationMatrix(R, I, mAccelerometer, mGeomagnetic);

        if (success) {
            float orientation[] = new float[3];
            SensorManager.getOrientation(R, orientation);
            // at this point, orientation contains the azimuth(direction), pitch and roll values.
              double azimuth = 180 * orientation[0] / Math.PI;
              double pitch = 180 * orientation[1] / Math.PI;
              double roll = 180 * orientation[2] / Math.PI;
        }
    }
}



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
    accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
}

@Override
protected void onResume() {
    super.onResume();

    mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_GAME);
    mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_GAME);
}

@Override
protected void onPause() {
    super.onPause();
    mSensorManager.unregisterListener(this, accelerometer);
    mSensorManager.unregisterListener(this, magnetometer);
}

}